Cross-feed for grinding machines



Patented Nov. 16, 1943 CROSS-FEED FOR GRINDING MACHINES Roger S. Pyne,Longmeadow, Mass, assignor to Van Norman Company, a corporation ofMassachusetts Application January 29, 1942, Serial No. 428,693

Claims.

This invention relates to cross-feeding mechanism particularly adaptablefor cylindrical, bore, and oscillating grinding machines. It has beenthe practice to employ cross-feed mechanism in which feeding impulseswere applied at one or both ends of each traverse, generally by a pawland ratchet device. In accordance with the present invention therotating grinding wheel and the work piece are repeatedly traversedaxially of each other, generally by moving one only of the members, andare caused to approach each other continuously instead ofintermittently. Since the wheel and work are approaching laterallyduring each traverse it might be supposed that a conical surface wouldbe produced. The rate of crossfeed relative to the traverse is so slow,however, that the tendency to produce a conical surface is notmeasurable on any but the longer work pieces; a condition aided by thefact that reversal requires a time period forming a substantial part ofthe traverse on the shorter work pieces. Since the cross-feed iscontinuing during reversal as well as during the actual traverse theamount of crossfeed during any one traverse period is very small.

A further object of the invention is to produce a cross-feed which maybe adjusted manually in either direction and at any time withoutdisturbing the cross-feed mechanism itself. Additional objects willappear from the following description and claims.

Referring to the drawing,

Fig. 1 is a front elevation of a cross-feed mechanism constructed inaccordance with this inven tion, with the manual operating shaft brokenaway and the front cover plate removed; the view being takensubstantially on line l-l of Fig. 2;

Fig. 2 is a section on line 2-2 of Fig. 1; and

Fig. 3 is a conventionalized wiring diagram.

. ince the improvement relates to the crossfeed mechanism only, thegrinding machine to which it is applied has not been shown. It will beunderstood that this may be an oscillating grinder such as shown forexample in the Van Norman, Stowell and Pyn Patent 2,149,409, March 7,1939, or any desired type of bore, cylindrical, or surface grinder whichemploys both a longitudinal traverse and a cross-feed. The crossfeedmechanism is mounted on the frame ll] of the machine in a casing I lcontaining a variable speed motor 12 preferably of th compound wounddirect-current type. The shaft l3 of the motor carries a worm l4engaging a worm wheel IS on a stub shaft l6 suitably journaled in thecasing and bearing a pinion IT. This pinion engages a gear l8 looselymounted upon a cross-feed drive shaft I9 here shown as bearing a pinion20 meshing with a gear 2| on the cross-feed screw 22. The gear l8 has afriction surface engaged by a friction drive member 23 forced againstthe gear by a spring 24 compressed between the member and a collar 25 onshaft Ill. The drive member 23 is keyed to shaft H3 at 25, and keyed tothe drive member at 2'! is a sleeve portion formed on a manual operatingwheel 28 preferably fitted with handles 29. The spring 24 is adjusted inforce so that the motor-driven gear [8 will drive shaft I9, and thus thefeed screw 22, positively under the very slight resistance offered bythe crossfeed. At the same time the shaft l9 may be turned by hand wheel28 in either direction without affecting the continuing operation of themotor drive. This differs from the usual ratchet feed, which may be fedforwardly by hand, but which cannot be fed rearwardly withoutdisconnecting the ratchet drive.

The variable speed motor I2 has been conventionally indicated in Fig. 3as a compoundwound direct current motor. One side of this motor isconnected to the line 30, while the other is connected to a plurality ofvariable resistances 3|, 32 made selectively available by a switch 33 inthe second side of the line. One of the rheostats 3| may be adjusted togive a motor speed suitable for coarse feed and the second rheostat 32may be adjusted for fine feed. The switch 33 may be controlled manuallyor by any suitable gauge mechanism, preferably through suitable relaysas described in the Van Norman et al. patent, to change from coarse tofine feed and then to open the circuit to terminate the cross-feedingoperarun.

It should be noted that there is thus available an infinite number ofspeeds, both coarse and fine; and that speed changes can be madeinstantly at any time during the operation of the mechanism.Furthermore, the friction mechanism provides for instant availability ofthe hand feed without necessity for operating any clutch mechanism. Thegrinding wheel may thus be brought into contact with the work by thehandwheel with assurance that automatic feed will be resumed withoutinterruption merely by discontinuing the application of force to thehandwheel; and at the termination of the feed may be backed off withoutdisconnecting the drive to motor l2.

What I claim is:

1. A cross-feed for a grinding machine comprising a mechanicalcross-feed train, a manual drive positively coupled to said train, a,friction drive coupled to said train and of a resistance sufiicientlylow to permit operation of the manual drive during continued engagementof the friction drive, a variable speed direct current motor coupled tosaid friction drive, a plurality of adjustable rheostats selectivelyconnected in series with the motor, and switch means for selectingbetween the rheostats.

2. A cross feed for a grinding machine comprising a mechanicalcross-feed train, a manual drive positively coupled to said train, afriction drive coupled to said train and of a resistance sufficientlylow to permit operation of the manual drive during continued engagementof the friction drive, a variable speed motor coupled to the frictiondrive, an irreversible driving element in the last-named coupling, andmeans for varying the speed of the motor.

3. A cross-feed for a grinding machine'comprising a mechanicalcross-feed train, a manual drive positively coupled to said train, afriction drive coupled to said train and of a resistance sufiicientlylow to permit operation of the manual drive during continued engagementof the friction drive, a variable speed direct current'motor coupled tosaid friction drive, an irreversible driving element in the last-namedcoupling, a plurality of adjustable rheostats selectively connected inseries with the motor, and switch means for selecting between therheostats.

4. A cross-feed for grinding machines comprising a feed screw, a drivingshaft coupled thereto, a handwheel having a sleeve portion surroundingthe shaft and fixed for rotation therewith, a friction element fixed forrotation with the shaft but slidable thereon, a second friction elementjournaled for free rotation about the shaft but fixed against slidingthereon, a spring surrounding the shaft and pressing against theslidable friction element, a, collar on the shaft adjustable to pressthe spring against the slidable friction element to force it against thesecond friction element, drive gearing for the second friction elementincluding a worm and worm wheel, a variable speed direct current motorconnected to the worm-,a plurality of adjustable rheostats selectivelyconnectible to the motor, and switch means for selecting between therheostats.

5. A cross-feed for a grinding machine of the type in which the work andwheel are repeatedly traversed axially of each other, comprising amechanical cross-feed train, a manual drive positively coupled to saidtrain, a friction drive coupled to said train and of a resistancesufficiently low to permit operation of the manual drive duringcontinued engagement of the friction drive, a variable speed motorcontinuously operating during said traverse and coupled to said frictiondrive for continuous operation thereof, and means for varying the speedof the motor.

ROGER S. PYNE.

